1. Field of the Invention
The present invention relates to a magnetic detection device having a detection element for sensing an external magnetic field, and a detection circuit for sensing an electric resistance of the detection element, and a method of manufacturing the magnetic detection device by using an anisotropic magnetoresistance effect (AMR effect), a giant magnetoresistance effect (GMR effect), and a tunnel magnetoresistance effect (TMR effect).
2. Description of the Related Art
A magnetic detection device for sensing an external magnetic field has been used so far as an ON-OFF switch of a noncontact type, and a rotary encoder for sensing a rotational phase or the number of rotations. A related magnetic detection device has been used as a magnetic detection device by using a hall element. However, since the magnetic detection device using the hall element needs a correction circuit, the detection circuit is complex. The magnetic detection element using a magnetoresistance effect has the advantage of making the circuit configuration of the detection circuit comparatively simple and that it is possible to detect an external magnetic field with high precision.
The magnetic detection device has the magnetic detection element and includes a magnetic detection element which is interposed between a detection circuit formed on a substrate and an insulating layer on the detection circuit. An interconnection layer forming the magnetic detection element and the magnetic circuit through a hole formed in the insulating layer is connected electrically.
In a semiconductor device, in JP-A-7-45616, for example, as shown in FIG. 2, an aluminum wiring formed on the substrate or a functional element such as a IC, is protected by covering a passivation layer (passivation film) having an insulating characteristic. A formation of the passivation layer is generally performed to separate the device from an external environment and to mechanically and chemically protect the device.
An example of the related art is disclosed in JP-A-7-45616 and JP-A-4-257238.
However, a surface of the passivation layer has a step surface when the magnetic detection element is formed into a film, and the magnetic detection element can not form a film with high precision. Accordingly, in JP-A-7-45616, although the stepped surface formed on the surface of the passivation layer is covered with a plasma-oxide layer and then a surface of the plasma-oxide layer is grinded, the method add complexity to the manufacturing process. So it is not preferable to use the above-mentioned method.
Accordingly, when the resist layer is used as a material covering a stepped surface of the surface of the passivation layer, a surface which is similar to a planar surface can be obtained without the grinding. However, a formation area of the resist layer has a problem in the above-mentioned process. That is, in accordance with the formation area of the resist layer, since there are many problems, such as cracks in the magnetic detection element formed on the resist layer and an electrode layer, a disconnection, or a peeling of the resist layer, it is not possible to manufacture the magnetic detection device having stable characteristics.